没有where子句与where子句的M​​ySql Update查询

Question

I am trying to reset some values in a large table having around 4 million records.

I just wanted to know which approach is better:

UPDATE TABLENAME SET VAL1=0, VAL2=0, VAL3=0;

or

foreach ( $catIds as $catId )
    execUpdate("UPDATE TABLENAME SET VAL1=0, VAL2=0, VAL3=0 WHERE CAT_ID='".$catId."';");

So the actual question is that is it safe to run it all at-once or the update should be broken into chunks?

Regards

Answer 1

Update should be broken into chunks. You can create partitions of the table. This way the execution is much more faster then direct query.